A tridimensional (3-D) x-ray method of evaluation of the shoulder was contrasted with six clinical and radiologic techniques used to evaluate shoulder subluxation, in 50 hemiplegic subjects. The 3-D evaluation is obtained through a mathematical computation associating two x-rays of the same shoulder, one taken at 0 degree (anteroposterior) and the other at a 45 degrees oblique view. A vector is thus obtained quantifying the separation from the apex of the humeral head to the inferior border of the glenoid fossa. The Y component (cephalocaudal) of this vector is used to represent the inferior displacement of the humeral head. The six other techniques of evaluation were: a) palpation, or the number of finger breadths inserted between the acromial process and the head of the humerus; b) anthropometry, or the distance between the acromial process and the lateral epicondyle of the humerus; c) templates, or the use of four schemas representing different degrees of separation of the humeral head from the glenoid fossa; d) a measure of the relation of the center of the humeral head to the center of the glenoid fossa; e) the vertical distance between the center of the humeral head and the center of the glenoid fossa; and f) the vertical distance between the apex of the humeral head and the inferior border of the glenoid fossa. Correlation coefficients contrasting the 3-D x-ray technique and the six other measures ranged from .738 to .995. The high level of precision and reliability of the 3-D measure indirectly validated the other measurement techniques.